Known interchangeable lens type of cameras have a driving motor forming part of a lens driving mechanism, such as an automatic focusing device or the like, in a camera body, a joint, i.e., driving, shaft for operatively connecting a driven mechanism on the interchangeable lens with the driving motor, and a mount locking member for locking the interchangeable lens in a predetermined locking position; all of these elements are provided on a camera body mounting surface (which is referred to hereinafter as a body mounting surface). The driving shaft and the mount locking member are continuously biased into a projected position in which they project outwardly from the body mounting surface, and these elements can be retracted from the body mounting surface. Namely, when a mounting surface of the interchangeable lens (which is referred to hereinafter as a lens mounting surface) comes into contact with the body mounting surface, the driving shaft and the mount locking member are forced into the body mounting surface by the lens mounting surface such that the outer projecting ends of the driving shaft and the mount locking member will be flush with the body mounting surface. Such a flush arrangement permits the interchangeable lens to rotate on the body mounting surface.
When the interchangeable lens is rotated into a predetermined position, the driving shaft and the mount locking member project outwardly from the body mounting surface so as to come into engagement in and with a locking recess formed in the lens mounting surface, and with a lens driving member (i.e., a driven member) of the interchangeable lens, respectively.
When the interchangeable lens is removed from the camera body, a mount lock releasing member is actuated in order to force the driving shaft and the mount locking member into the body mounting surface. The lock release is preferably effected by a single lock releasing member. To this end, the driving shaft and the mount locking member are usually arranged in the same quadrant of the body mounting surface (as defined by coordinates having their origin along the optical axis of the lens, when viewed from the front of the camera body), in a conventional interchangeable lens type of camera.
This arrangement of the driving shaft and the mount locking member in the same quadrant ensures the close positioning of the driving shaft to the mount locking member, thereby resulting in the realization of a simple and compact construction of the driving shaft and of the mount locking member in association with the single mount lock releasing member.
On the other hand, a mode selection switch is usually provided in a conventional interchangeable lens type of camera in order to select an automatic focusing mode or a manual focusing mode. Additionally, in a camera having an automatic focusing device, the automatic focusing mode generally has two modes, i.e., a first mode in which the focusing operation will have priority, which is hereinafter referred to as the focusing priority mode, and a second mode in which the releasing operation has priority, which is hereinafter referred to as the releasing priority mode. In the manual focusing mode, the operator can manually adjust focusing.
In camera having a mode selection mechanism as disclosed above, the driving shaft is associated with the mode selection switch, such that the driving shaft is held in a connected position, i.e., a projected position in which the driving shaft projects from the body mounting surface and is operatively or kinematically connected to the driven member on the lens, in the automatic focusing mode, and is thus held in a disconnected position, i.e., in a retracted position in which the driving shaft is disconnected from the driven member in the manual focusing mode. Disconnection of the joint shaft from the driving member, i.e., from the distance ring, on the lens contributes to reduced power in manual operation, when in the manual focusing mode.
It is preferable to provide the mode selection switch in a location such that an operator can actuate the mode selection switch either by his or her left hand. This is because an operator usually holds a camera body with the operator's right hand, and actuates focusing, e.g., with the operator's left hand. Preferably, the mode selection switch is arranged on the right side of the camera body, and in particular in the fourth quadrant defined by the coordinates of the body mounting surface, as viewed in a front elevational view of the camera body.
On the other hand, the mount lock releasing member is usually located either in the third quadrant, i.e., the left side, or in the fourth quadrant, i.e., the right side, of the mounting surface of the camera body, since it is not usually necessary to actuate the mount lock releasing member when a photograph is being taken. When the mode selection switch is located on the right side, i.e., on the fourth quadrant, of the camera body because of the reasons mentioned above, the mount lock releasing member is preferably located on the left side, i.e., the third quadrant, in order to prevent interference, during actuation, between the mode selection switch and the mount lock releasing member.
The driving shaft and the mode selection switch should be located close to each other, because when the manual mode is selected by the mode selection switch, the driving shaft is associated with the mode selection switch in such a way that the driving shaft is retracted from the body mounting surface, as mentioned above. Specifically, if the mode selection switch is located in the fourth quadrant, the driving shaft should also be located in the fourth quadrant.
Under these circumstances, the most preferable arrangement is when the mount lock releasing member is positioned in the third quadrant, and the driving shaft and mode selection switch are provided in the fourth quadrant, thus taking the operation of these elements into consideration.
However, in this most preferable arrangement, a problem occurs in that the connecting mechanism located between the mount lock releasing member and the joint shaft is located far from the mount lock releasing member. Specifically, the problem which occurs and which needs to be solved is to provide a simple and compact connecting mechanism between the movable elements (the driving or drive shaft, the mount locking member, and the mount lock releasing member) of the camera within a limited camera space while minimizing the transmission loss.
In addition to the above, electrical contacts are normally provided on the body mounting of the camera in order to transmit and receive information (various electrical signals) between the camera body and the interchangeable lens in an interchangeable lens type of camera. These contacts are usually located on the lower portion of the mounting. The location of the contacts on the lower portion of the mounting increases the distance between the mount lock releasing member and the driving shaft, thereby making it difficult to achieve a small and compact arrangement for the connecting mechanism which is discussed above.